For a variety of reasons, documents must be presented in their original format, with certain material, such as text or illustrations, redacted. For example, in response to Freedom of Information Act requests, U.S. Government agencies must release certain documents. Often, these documents contain information which is exempt from disclosure under FOIA. The documents themselves are released in their original format, but the material that is exempt from disclosure must be removed. In other situations, such as in litigation, counsel may wish to provide a document in response to a discovery request, but remove privileged portions of the document.
Traditionally, the primary method of redacting information from documents was to take a physical copy of the document, and cover over the text and images to be redacted. Covering would be done manually with tools such as a black marker, a grease pencil, or strips of opaque tape. This process is slow and labor intensive. Also, on review of the redacted document, if the reviewer determines that information which is required to be disclosed has been redacted, it is difficult to correct such errors. Once the process is completed, the document can be photocopied and a photocopy furnished to the requester. Many U.S. Government agencies have been placing such documents on World Wide Web servers to make the documents available over the Internet. The documents must be scanned before being placed on the Web server.
Methods have been developed to perform redaction of electronic documents. Typically, these methods operate on tag image file format (TIFF) files. Conventionally, these products employ overlays of opaque blocks of color to cover information in the TIFF document.
A variety of disadvantages are associated with TIFF files, particularly when compared with the portable document format (PDF) files in the format developed by Adobe Systems, Inc. For example, in the TIFF format, designers have great flexibility in creating tags, which results in certain applications not being able to read all TIFF files. More recent versions of TIFF are not interchangeable with older versions. Also TIFF files for the same document are much larger than comparable PDF files. The overlays of opaque blocks of color, ordinarily saved separately from the document pages, causes a delay when a document is opened while the overlays are placed by software on the page. Generally, custom programming and system integration is required for the TIFF programs to be operational, because not all applications are compatible with TIFF files. If the overlays of blocks of color are not properly embedded in the document, it is possible for the overlays to be removed. The software packages that are commercially available for redaction of TIFF files are only available for certain operating systems, and do not operate on a variety of platform. For example, such systems are not compatible with both systems that operate on Windows PC's and Macintosh PC's. Finally, if large portions of the text are removed, the opaque blocks of color tend to be very large. This can render printing of the documents to be problematic.